LSB隐写术的密钥恢复方法

Approaches for Recovering Key of LSB Steganography

作为隐写术安全性分析的重要手段,隐写分析已成为信息隐藏领域的一个研究热点。而通过恢复隐写密钥来提取隐藏的消息是隐写分析的主要目的之一。为了研究如何搜索隐写密钥,首先在"已知载体"和"载体被重复使用"条件下,分析了恢复LSB隐写术密钥的计算复杂度。然后在"载体被重复使用"条件下,对图像空域LSB隐写术提出了一种新的密钥恢复算法。该算法借鉴了密码分析中的"分别征服攻击"思想,使计算复杂度由O(22r)降至O(2r)。实验结果表明了该算法的有效性。

As an important way of security analysis for the steganography, steganalysis has become a concernful topic in the field of information hiding. And extracting the hidden message by recovering the stego key is one of main aims of steganalysis. To study how to search for the key of LSB steganography, firstly the theoretic analysis for the computational complexity of key recovery on LSB steganography are made under the condition of 'known cover' and 'cover being repeatedly used' respectively. Then under the latter condition, a key recovering method for LSB steganography of spatial images is presented,which can reduce the computational complexity from O(2^(2r)) to O(2~r)by using the idea of 'divide and conquer attack'.And the experiment results show that this method is effective.